An improvement in electro-mechanical sweeping or wiping systems has been proposed, which comprises:
a regulating means for generating an electrical control signal which changes as a function of time in accordance with a demanded sweeping characteristic, and PA1 at least one wiper motor control means, comprising a wiper motor, a control stage for the said wiper motor, a detector for detecting the angular position of a part driven by the motor, and a feedback circuit for applying to the motor control stage an electrical error signal representing the difference between the control signal and a signal representing the actual detected position.
This new arrangement is of great importance, to the extent that is considerably simplifies the design of sweeping apparatus such as a windshield wiper installation. In particular, it eliminates the need for a mechanical linkages because the motor shaft is alternately rotated clock and anticlockwise.
In addition, it considerably increases the range of possible modes of sweeping or wiping angles which may be obtained, for example multiple speeds, intermittent operation, and the provision of a parking position for the windshield wipers.
It has however been noted that under exceptional conditions, the control system may prove unable to force one of the motors to be in the demanded position in its arc of sweep at each point in time, this is while only a disadvantage with a single windshield wiper, it is a much greater drawback where there are a plurality of windshield wipers, since the wipers may then be in a condition to interfere with each other.